Two identical pith balls are charged by rubbing against each other
PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Two identical pith balls are charged by rubbing against each other. They are suspended from a horizontal rod through two strings of length 20 cm each, the separation between the suspension points being 5 cm. In equilibrium, the separation between the balls is 3 cm. The tension in the string is \_\_\_\_\_. The charge on each ball has a magnitude 2.0×10−8 C.
(a) 8×10−2 N
(b) 6.2×10−2 N
(c) 8.2×10−3 N
(d) 6.2×10−3 N